The invention relates to a communication system which is suitable for the carrying out of services, especially interactive communication services. More in particular, the invention is related to a communication system comprising a first communication path between a services station and a user station, as well as a second communication path between the user station and the services station, the user station being arranged for the issuing of data packets and the user station being arranged for the reception of data packets.
Offering user information to users in a telecommunication system by way of service via a first communication path, for example a cable network, is known in the art. Such information, which in general comprises audio-visual information (such as films), is transmitted from a services station (such as a so-called server) to the users via the cable network. In this regard the users have a user station (terminal) such as a PC or a television set on which the user information concerned is received.
For various services it is desirable that users can transmit selection information to the services station, where this selection information can contain control commands, for example. Thus users can choose from a list of films, supply answers in TV games or control an object, and so on. If the user station comprises a television set, a telephone set is often used for transmitting the selection information.
The need for integrated solutions for user stations, in which the station is suitable both for receiving and displaying user information and for the entry of selection information by the user and the transmission thereof to the services station, is making itself more and more felt. To this end, integrated stations (terminals) are proposed, which are arranged for the issuing of selection information in the form of data packets, such as ATM cells.
In this regard, the problem arises that existing communication systems comprise networks which are not arranged for the transmission of data packets. The public telephony network ("PSTN" or "Public Switched Telephone Network"), for example, has no provisions for the transmission of data packets. It is therefore necessary that the data packets, which are issued by the said stations, are converted into data which indeed can be transmitted over the telephony network. Furthermore, services stations must be arranged for the reception of data which are transmitted in various forms. This brings with it the necessity of providing different interfaces for different network services at one services station, which is expensive. It is also possible to connect the user station to the services station by means of a special network which is arranged for the transmission of data packets. Such a special network is expensive, however, and can not be applied everywhere.
It is known from the Prior Art to transmit voice band signals via an ATM network, as e.g. disclosed in EP 0 690 653 and EP 0 722 237. It is also known to transmit data packets using a telephone switching network, as e.g. disclosed in EP 0 418 812.
A system in which messages are broadcast and in which a call-back facility is used, is disclosed in U.S. Pat. No. 4,713,837. Said U.S. Patent does, however, not deal with consumer services but with the remote reading of meters for the purpose of electronic billing. Furthermore, said Patent does not disclose the transmission of data packets via PSTN.
Other Prior Art may be found in GB 2 280 337 and GB 2 282 027. All said Prior Art documents are herewith incorporated by reference in this text.